Some work machines are useful to repetitiously perform processes of digging and loading. For example, a work machine, such as a wheel loader, may repetitively load material into its bucket and dump the material into the bed of a truck. Often, the repetitious work cycle can become tedious to an operator and the operator may become fatigued. As the fatigue sets in, the operator may work less efficiently, thereby adversely impacting the efficiency of the work machine.
To reduce operator fatigue and maintain a high level of machine productivity and efficiency, some work machines are equipped with controllers that automate portions of the repetitive work process. These controllers typically rely upon measured cylinder pressures and positions to determine when to implement an action or a step to load the bucket of the work machine. While these pressure and position measurements may be useful when loading an aggregate, such as gravel or sand that is loosely piled, such systems are less useful when digging hard materials. When digging and loading materials with different digging toughness and shapes, some work machines may require that an operator tune or otherwise adjust the work machine to compensate for the digging toughness.
One example of a system for automatically digging and loading is disclosed in U.S. Patent Publication No. 2004/0117092. The system disclosed in the publication may be used to efficiently perform a repetitive motion, such as digging and loading with the work machine. Nevertheless, the system may be improved upon. For example, while the system disclosed in the publication provides for adjustment of lift and tilt commands based upon variations in a monitored ground speed, it may not provide for adjustment of speed based on velocities of the lift and tilt actuators. Further, such a system may still require tuning and adjustment when loading piles of materials having differing densities and materials.
This disclosure is directed to an automatic control system and method that overcomes one or more of the disadvantages of the prior art.